KuroiNeko-Chan

What kind of game are trying to play? One of the music games, a job or an infra red game? Infra red games can only be played with two tamas. If it's doing that when you're trying to play a job or music game, maybe you should try changing the battery. Otherwise, maybe it's broken?

Amat Gotchi

Did you select the fourth icon or the 8th icon? The fourth icon (shaped like a music note) is to play games, and change instruments and toys by yourself. The 8th icon (shaped like a heart) is for playing games and exchanging items with another Tamagotchi via infrared connection.

To play a game on your own, select the fourth icon, and then choose "MUSIC GAME." You will have a choice of 3 games to play. Play one of them, and your Tamagotchi will earn skill points.

If this is not the case, try taking the battery out then putting it back in or, like KuroiNeko-Chan says, changing it. You may also have a broken Tamagotchi.